Process of making friction facings



umrso STAUTES PATENT orFlcrammmcx o, s'ranLEY, or BRIDGEPORT, commence-r, ASSIGNOR 'ro mns'ros GOMPANY, or rnmenron'r, commences, A CORPORATION or oomrncrrco'r.

PROCESS. OF MAKING FRICTION FACINGS.

No Drawing. Application filed September 24, '1919, Serial No. 325,915. Renewed October 28, 1921. Serial No. 511,105.

To all whom it may concerm.

a citizen of the United States, residing in the cityof Bridgeport, county of Fairfield, and State of Connecticut, have invented certain new and useful Improvements in Processes of Making Friction Facings, of which the following is a specification.

This invention relates to improvements in process of making friction facings and refers more particularly to a clutch facing or brake lining gdapted for use in motor. ve-

, hicles.

The inventlon is directed to a novel process of making a friction facing from felted unwoven asbestos fibre saturated with a binder. The object of the invention is to provide processby which the friction facing has a maximum tensile strength and hardness so that it can Withstand the shocks to'which these facings are subjected in a motor car and also will have suflicien't resistance to abrasion; while at the same time it has the proper co-eflicientof friction. necessary that the binder in these facings must be unaffected by oil or water in use,

.which object is accomplished by the present invention without in any way detracting from the other characteristics. 1 i

The processniay be carried out as follows:

Asbestos fibre preferably the short or low grade fibreris first ground in a suitable grinding machine or cutten. The ground material is then put into a beater mixed with the water or other. solution and beaten into a pulp. The pulp is then delivered-to a paper making machine as for'example a wet board machine and formed into sheets or boards of suitable width and thickness.- ,This forms an unwoven felted sheet.

As a feature of the invention, there is mixedwith the pulp in the beatef a sulphurizingl agent, as for example sulphur, lead sulp ide or analogous sulphides. In using sulphide asa sulphurizing agent, the amount,

employed is approximately 1.6 per cent by the weight of the asbestos fibre although this can be varied according to the characteristics of the product desired. This sulphurizin agent facilitates or hastens the cure of the inder and adds to the strength of "theproduct and also converts the. binder into a form insoluble by oil or water.-

also

It is also 7 tends to produce a uniform curing through- Be it known that I, FREDERICK C. STANLEY,

out the mass during the curing operatlon hereinafter described. .It is to be noted that formed as described, they are subjected to hydraulic pressure in suitable presses and Specification of Letters Patent. Patented J une 2% 1922,v

are then hung up to dry in a drying room of sufficient temperature to remove the water. The sheet is then calendered to the desired thicknessand the friction facings are'then The sheets are sub-; 1

out out of the sheet.

jected to su cient pressure in the calender to obtain as much tensile strength in the dry sheet as is feasible. The friction facings Whether clutch rings or brake linings are now ready for saturation. -The saturatin tank is filled with a binder. 'This binder may consist of 94 per cent of linseed oil, 6

percent of gilsonite in the solution in the oil,

thinned with gasoline to about 33 Baum gravity. The friction facings'are then immersed while suspended on suitable rods in this binder solution fora period ofhalf an hour. The friction "facingsare then removed and put ina closed steam oven and main tained at a temperature of about 200 F. to

drive off the gasoline which gasoline may be recovered and saved. This steam treatment is preferably continued from two to three hours. The friction. facings are then. removed to a closed baking oven where they are subjected to atemp'erature of about 250 'F for a period of twelve hours. The facings are then taken out of the oven and immersed in another saturating tank containing a solution 66 percent of linseed oil and 33 per cent of gasoline, the gravity of the solution being about 33 Baum. This second immersion takes place for from two to three-- minutes. In both of the saturating steps double boiled linseed oil is preferable. The

friction facings are then put into a second closed baking oven and, maintained at a temperature of 300 F. for twenty four hours. The heat in both of the baking ovens is preferably dry heat. The friction facings are then removed'from the second overg and sand papered tomicrometer size and smooth finish to the facing. The facings are now ready for use. p

I have givenabove an, illustration in to get a.

ioo

\ oil, due to the presence of the water in the which the process is actually carried out in commercial operation. It is to be understood that the temperature and length of,

treatment are subject to reasonable variations depending on the 'flexibillty I and .Als oils other than linseed oil may perhaps in ertain cases be used and other asphalts strjngth required in the finished product. j

stitutedffor gilsonite: During the baking operation, the linseed oven and also to the sulp'hurizing agent of the sheet is sulphurized to produce a tough hard'binden. The solubility of the linseed oil before the baking treatments is'practically. 100% in the gasoline while after the baking treatments it is very materially re; duced; and in fact the baking operation may be so carried out as to make the oil practically insoluble in gasoline. It is to be noted that by means of the double saturation and 7 double baking, a more efficient curing of the binder is obtained and the sheet can be impregnated withlarger quantities of binder. This adds greatly to the tensile strength and hardness of thefinished product.

- The strength and hardness of the product made by this process is far in excess of 3000.

to 4000 lbs'., upwards in tensile strength, over that heretofore obtained from any unwoven saturated friction facing and'is even stronger. than a ,woven sheet. The Brinnell hardness also is proportionately increased over the friction facings heretofore made and is above15. It is to be noted that in the baking operation, the reaction develops autogenous heat or in other words exo-thermic and care must be taken to revent the material from becoming so highly heated as to catchfire. This exo-thermicreaction results in the fact that the sulphurization is of such a character as to generate-"heat in ad.-

dition to that. externally applied. This exo-' thermic reaction of sulphurizationis well known in other arts as for example in the manufacture of air blown asphalt from pctroleum residuum. I

The article produced by the herein described rocess is claimed in my application Serial 0. 405,508.

I claim as my invention:

1. A process of making a friction facing consisting in mixing asbestos pulp with the saturationin a sulphuriza le binder, baking the saturated facing at such a temperature asto cause pronounced action between the sulphur and the binder.

2. A process of making a friction facing consisting in mixing asbestos pulp with the sulphurizing agent, forming unwoven friction facings of desired size and configuration therefrom, subjecting the facings to a saturation in a sulphurizable binder, baking the saturated facing at such a temperature as -to cause pronounced action between the sulphur andthe binder and subjecting the facing to a second saturation and a second baking to produce a maximum tensile stren h and hardness.

3. process of making a friction facing consisting in mixing asbestos pulp with the sulphurizing agent, forming unwoven friction facings of desired size and configuration therefrom, subjecting the facings to a.

saturation in a sulphurizablebinder, such as linseed oil, baking the saturated facing at sue a temperature as to cause pronounced act on between the sulphur and the binder.

.4. A process of making a friction facing consisting in mixing asbestos pulp with the sulphurizi'ng agent, forming unwoven friction facings of desired size and configuration therefrom, subjecting the facings to a saturation in a sulphurizable binder, such as linseed oil, baking the saturated facing at such a temperature as to cause pronounced action between the sulphur and the binder and subjecting the facing to a second saturation and a second baking to produce a maximum tensile strength and hardness.

5; The process of making a frictionfacing consisting in forming friction facings of the desired size from material containing incombustible fiber, subjecting the facing to a saturation in a sulphurizable binder, and baking the saturated facings in the presence of a sulphurizing agent and at such temperature asto. cause pronounced action between the sulphur and the binder, and sub. jecting the facing to a second saturation and a second "baking.

" FREDERICK o. STANLE 

